According to 9to5Mac, Apple apparently plans to drop support for 32-bit apps in iOS 10.3.
The alert dialog presented when launching a 32-bit app on iOS 10.3 beta 1 now warns users that the app needs to be updated to continue working on future versions of iOS. This suggests that iOS 11 could be the first version to only support 64-bit apps, according to 9to5Mac. iOS 11 will almost certainly be previewed at this summer's Apple Worldwide Developer Conference.
Apple has supported 64-bit apps on iOS since the launch of the iPhone 5s in September 2013. The company has also required developers submit new apps with 64-bit support since February 2015 and app updates since June 2015.
While legacy 32-bit apps still in the App Store have continued to be supported, iOS 9 included an alert when first launching 32-bit apps that told users the legacy app may slow down device performance.